Book Review: Empire Of The Sum

The success of the pocket calculator relied on operational simplicity, but it involved a complex process of false starts, slow advances, and ingenious thinking.

The book ‘Empire of the Sum’ by Keith Houston charts the development of the pocket calculator, delivering a fascinating, witty tale. The human search for reliable ways of counting has been long and circuitous, ranging from notches on bones to the abacus to clunky mechanical machines.

The author has a good time hunting down some of the attempts of the 19th century; most of them did not work very well, but they laid the groundwork for later improvements. War and navigation were the key drivers in the search for arithmetic accuracy, and the author introduces us to a cast of colorful characters along the way.

He takes a variety of fun detours, such as a discourse on the history of pockets and a discussion of the Curta, a

hand-held calculating device of gears and wheels. Slide rules became essential tools for the numerically minded, and the development of crank-operated accounting machines was a huge step forward. But the real genesis of the pocket calculator came with the Casio line, which switched the focus from mechanics to electronics.

The next major improvement was the addition of built-in formulae and logarithmic tools, which turned arithmetic into math. The author unpacks the breakthrough products, including the Hewlett-Packard HP-35 and the Texas Instruments TI-81. He believes that the heyday of the pocket calculator was the 1980s and ’90s.

After that, cellphones and laptops became unbeatable competition. However, the fact that these digital advances integrated calculators into their operations meant that the idea lived on, albeit in another form. “The calculator is dead; long live the calculator,” he concludes.

Empire of the Sum is an entertaining, informative story about a technology that defined an era.